Researchers at the University of Cambridge developed wearable charge storing components incorporated directly into fabrics.
The devices could be used in flexible circuits, and applications such as healthcare monitoring, energy conversion. Other potential commercial opportunities for the technology include fashion, wearable energy and data storage, wearable computing, and military garments.
The Cambridge researchers, in collaboration with colleagues at Jiangnan University in China, demonstrated how graphene and other related materials can be directly incorporated into fabrics to make charge storage elements like capacitors. Such wearable energy storage devices are washable, flexible, and comfortable. (See image above Copyright ©University of Cambridge).
“Turning textiles into functional energy storage elements can open up an entirely new set of applications, from body-energy harvesting and storage to the Internet of Things,” said Dr Felice Torrisi from the Cambridge Graphene Centre. “In the future our clothes could incorporate these textile-based charge storage elements and power wearable textile devices.”
The research, detailed in the journal Nanoscale, demonstrates that graphene inks can store electrical charge and release it when required. The new textile electronic devices use low-cost, sustainable, and scalable dyeing of polyester fabric. The inks are made with standard solution processing techniques.
Building on previous work from the same team, the researchers created inks that can be directly coated onto a polyester fabric with a simple dyeing process.
The process allows various kinds of electronic components to be incorporated into the fabric.
Most other wearable electronics use rigid electronic components mounted on plastic or textiles.
However, such rigid components often offer limited compatibility with the skin, are damaged when washed, and can be uncomfortable to wear.
“Other techniques to incorporate electronic components directly into textiles are expensive to produce and usually require toxic solvents, which makes them unsuitable to be worn,” said Dr Torrisi, the paper’s corresponding author. “Our inks are cheap, safe and environmentally-friendly, and can be combined to create electronic circuits by simply overlaying different fabrics made of two-dimensional materials on the fabric.”
The research team suspended individual graphene sheets in a low boiling point solvent, which can be easily removed after deposition on the fabric.
This effort resulted thin and uniform conducting network composed of multiple graphene sheets.
The subsequent overlaying of several graphene and hexagonal boron nitride (h-BN) fabrics makes an active region, which can store a charge. This bendable kind of ‘battery’ on fabric can withstand washing cycles in a regular washing machine.
“Textile dyeing has been around for centuries using simple pigments, but our result demonstrates for the first time that inks based on graphene and related materials can be used to produce textiles that could store and release energy,” said co-author Professor Chaoxia Wang from Jiangnan University in China. “Our process is scalable and there are no fundamental obstacles to the technological development of wearable electronic devices both in terms of their complexity and performance.”
The team demonstrated a fully textile-based capacitive heterostructure with a capacitance of 26pF/cm2 and the flexibility of 1cm bending radius.
Support for the research came from the Engineering and Physical Science Research Council, the Newton Trust, the Ministry of Science and Technology of China, and the Natural Science Foundation of China. Cambridge Enterprise, the university’s commercialization arm is attempting to commercialize the technology.
Qiang, S., et al. Wearable solid-state capacitors based on two-dimensional material all-textile heterostructures. Nanoscale (2019). DOI: 10.1039/C9NR00463G